| 摘要 |
<p>Complaint universal (CU) substrates (10) and techniques for forming the same facilitate growth of epitaxial layers (18) comprised of materials which are highly lattice mismatched with the substrate material. The CU substrates employ very thin (e.g., 1-20 nm or less) substrate layers (14) which are loosely bonded to a thick bulk material base layer (12). Because of the loose bonding, the bonding energy of the atoms in the thin substrate layer is reduced, thus greatly increasing the flexibility of the thin substrate layer. This enables the substrate layer to absorb strain or stress imparted during the growth of lattice mismatched epitaxial layers, thus avoiding the formation of defects in the epitaxial layers. The thin substrate layer can be bonded at an angle relative to the base layer so that screw dislocations form which provide the desired reduction in bonding energy and increase in flexibility. Reducing bonding energy can be accomplished by making the base material porous at the top surface, or by patterning or roughing the top surface.</p> |
